Aromatic monomers deriving from glycerol units, process for their preparation and use thereof for the preparation of water-soluble conjugated polymers

ABSTRACT

Monomers having formula (I) and process for their synthesis which comprises the etherification reaction of a halogen-derivative (Z═Cl, Br, I) having formula (III) with the hydroxyl group of the glycerol derivative (IV), according to the following scheme:

The present invention relates to aromatic monomers deriving fromglycerol units and the process for their preparation as well as theiruse for the preparation of conjugated polymers/copolymers soluble inwater or aqueous mixtures.

As is known, photovoltaic devices are devices capable of converting theenergy of a light radiation into electric energy. At present, mostphotovoltaic devices which can be used for practical applicationsexploit the physico-chemical properties of photoactive materials of theinorganic type, in particular high-purity crystalline silicon. As aresult of the high production costs of silicon, scientific research,however, has long been orienting its efforts towards the development ofalternative organic materials having a conjugated, oligomeric orpolymeric structure. Unlike high-purity crystalline silicon, in fact,conjugated organic materials are characterized by a relative synthesisfacility, the possibility of modulating the physico-chemical properties,a low production cost, a reduced weight of the relative photovoltaicdevice, in addition to allowing the recycling of said polymer at the endof the life-cycle of the device in which it is used.

The functioning of organic and polymer photovoltaic cells is based onthe combined use of an electron acceptor compound and an electron donorcompound. In the state of the art, the most widely-used electron donorand acceptor compounds in the devices indicated in scientific and patentliterature are π-conjugated copolymers, especially those belonging tothe groups of polyparaphenylene vinylenes and polythiophenes, andderivatives of fullerene, respectively.

The basic conversion process of light into electric current in a polymerphotovoltaic cell takes place through the following steps:

1. absorption of a photon on the part of the donor compound with theformation of an exciton, i.e. a pair of “electron-hole” chargetransporters;2. diffusion of the exciton in a region of the donor compound in whichits dissociation can take place;3. dissociation of the exciton in the two charge transporters (electron(−) and hole (+)) separated;4. transporting of the charges thus formed to the cathode (electron,through the acceptor compound) and anode (electronic hole, through thedonor compound), with the generation of an electric current in thecircuit of the device.

The photo-absorption process with the formation of the exciton andsubsequent yielding of the electron to the acceptor compound leads tothe transfer of an electron from the HOMO (Highest Occupied MolecularOrbital) to the LUMO (Lowest Unoccupied Molecular Orbital) of the donorand subsequently the passage from this to the LUMO of the acceptor.

As the efficiency of an organic or polymer photovoltaic cell depends onthe number of free electrons which are generated by dissociation of theexcitons, one of the structural characteristics of donor compounds whichmostly influences said efficiency is the difference in energy existingbetween the HOMO and LUMO orbitals of the donor compound (so-calledband-gap). The wave-length of the photons which the donor compound iscapable of collecting and effectively converting into electric energy(so-called “photon harvesting” or “light harvesting” process) depends,in particular, on this difference.

The efficiency of a cell is also proportional to the voltage obtainablein the device. It has been demonstrated that the voltage is correlatedto the energy difference between the HOMO of the donor and LUMO of theacceptor compound. It is therefore evident that also in this case theenergy levels of the materials selected have a fundamental importance.

Another important characteristic is the mobility of the electrons in theacceptor compound and electronic gaps in the donor compound, whichdetermines the facility with which the electric charges, oncephotogenerated, reach the electrodes. This, in addition to being anintrinsic property of the molecules, is also greatly influenced by themorphology of the photoactive layer which, in turn, depends on thereciprocal miscibility of the components and on their solubility.Finally, a further fundamental characteristic is the resistance tothermo-oxidative and photo-oxidative degradation of the materials, whichmust be stable under the operating conditions of the device.

In order to obtain acceptable electric currents, the band-gap betweenHOMO and LUMO must not be excessively high but at the same time it mustnot be excessively low, as an excessively low gap would jeopardize thevoltage obtainable at the electrodes of the device.

In the simplest way of operating, the cells are produced by introducinga thin layer (about 100 nanometres) of a mixture of the acceptorcompound and donor compound between two electrodes. In order to producea layer of this type, a solution of the two components is prepared. Aphotoactive film is subsequently created on the first electrode startingfrom the solution, resorting to suitable deposition techniques such as“spin-coating”, “spray-coating” “ink-jet printing” and similar. Thecounter-electrode is finally deposited on the dried film.

Donor materials consist of conjugated aromatic polymers. One of thosewhich is most commonly used in the construction of polymer solar cellsis regioregular poly(3-hexylthiophene). This polymer has suitableelectronic and optical characteristics (HOMO and LUMO orbital values;absorption coefficient), a good solubility in the organic solvents usedfor the construction of the cells and a reasonable mobility of theelectronic gaps.

Current technologies for the production of polymer cells resort todepositions techniques of thin photoactive layers from solution, coupledwith high vacuum processes for the production of the electrodes (or ofthe same photoactive layer, in case of cells based onlow-molecular-weight organic molecules). The deposition from polymersolution resorts to drop casting, spin coating, dip coating spraycoating, ink-jet printing, screen printing, roll-to-roll depositionprocesses etc., and the use of a suitable solvent. The donor polymersare normally dissolved in organic solvents such as toluene, xylene,chloroform, chlorobenzene etc. to guarantee complete solubility. Thesesolvents however are extremely toxic and it is therefore desirable toeliminate them in industrial processes. It would be extremely beneficialto use polymers soluble in aqueous, alcohol solvents or also inhydro-alcohol mixtures or water/acetone, water/dioxane,water/tetrahydrofuran mixtures etc. In this way, in addition to thetoxicity, hazards deriving from the potential occurrence of explosionsdue to the formation of explosive mixtures between air and vapours oforganic solvent or drops of finely divided organic solvent, would besignificantly reduced.

Due to the chemical structure of the polymers used, however, thesolubility of these in water or aqueous mixtures, is practically null.

The Applicant has now found a new group of functionalized aromaticmonomers which can generate conjugated polymers/copolymers which aresoluble in water or aqueous mixtures.

An object of the present invention therefore relates to monomers havingthe following general structure (I):

wherein

-   -   Ar is a C₆-C₁₂ aromatic radical, a C₁₂-C₁₈ polycyclic aromatic        radical, or Ar is a heteroaromatic radical containing one or        more heteroatoms such as S, N, Se, O, optionally polycondensed,    -   X is a group which can be polymerized by means of a reaction        selected from Suzuki, Stille, Heck or Yamamoto reactions,        selected from —Br, —Cl, —I, —O—(SO₂)—CF₃, (OH)₂, —B(OR′)₂,        —SnR′₃, —B(OR″O) and vinyl, with R′ a C₁-C₆ alkyl radical and R″        an ethylene radical, optionally substituted with C₁-C₂ alkyl        groups;    -   R₁ and R₂, equal or different from each other, can be a hydrogen        atom or a C₁-C₆ alkyl radical;    -   R is a divalent C₁-C₁₂, preferably C₁-C₆, alkylene radical;    -   n ranges from 1 to 4, and is preferably 1 or 2.

Preferred monomers according to the present invention are those whereinAr is a radical deriving from benzene, fluorene, thiophene, carbazole,dithienocyclopentadiene or phenothiazine.

Monomers having the following general formula (II) represent a furtherobject of the present invention:

-   -   wherein R, R₁, R₂, Ar, X, n have the same meanings as indicated        above; and    -   Ar′ represents a heteroaromatic radical containing a heteroatom        such as S, N, Se;    -   m=1 or 2, m is preferably 1.

Preferred monomers according to the invention are those wherein Ar′ is aradical deriving from thiophene, thieno-thiophene, thiazole, carbazole,dithienocyclopentadiene or phenothiazine.

Monomers having general formula (I) and (II) can be prepared bytraditional chemical synthesis techniques. The synthesis of (I), forexample, takes place through the etherification reaction (Williamsonreaction) of a halogen derivative (Z═Cl, Br, I, preferably bromine)having formula (III) with the hydroxyl group of the glycerol derivative(IV), according to the following scheme 1:

This type of reaction is known in literature, it is described, forexample, in the U.S. Pat. No. 3,960,902. These reactions normally takeplace in the presence of bases, such as alcoholates, (methylate,ethylate, butylate, terbutylate) of alkaline metals (sodium, potassium,caesium, preferably potassium terbutylate). The reaction is carried outin organic solvents, selected from ethers (for example tetrahydrofuran,dimethoxyethane, etc.), hydrocarbons (benzene, toluene, xylene, etc.),dipolar aprotic solvents (N-dimethylformamide, N-methylpyrrolidone,etc.). The molar ratios III:IV:base used range from 1:1.1:1.15 to1:3:3.3. The reaction is carried out at temperatures ranging from 15° C.to 150° C., preferably from 20° C. to 80° C. These reactions can also becarried out under phase transfer conditions.

The halogen derivative (III) is synthesized by means of normal organicsynthesis techniques, for example alkylation with dihalogen derivatives(VI) (Z═Cl, Br, I) of aromatic systems (V) containing acid hydrogen(easily removable by base treatment), according to the following scheme2:

The synthesis of halogen derivatives (III) is known in the art, someexamples present in literature are: Macromol. Rapid Commun. 2008, 29,390; JACS 2003, 125, 6705; Synthetic Metals 2007, 157, 813; JournalPolymer Science: Part A: Polymer Chemistry 2008, 46, 4407.

The glycerol derivative (IV) can be prepared using normal synthetictechnologies, by the acid catalyzed reaction of glycerine (VII) with aderivative containing a carbonyl functionality (VIII), R₁ and R₂ havethe meanings previously defined in general formula (I). The reaction isdescribed by scheme 3:

The synthesis of these compounds is known in the art, this reaction iswidely described in Synthesis 1981, 501.

The compounds having general formula (II) are prepared starting from thecompounds having general formula (I) by means of a metal-assistedcondensation reaction and subsequent halogenation of the derivativeobtained. The compounds having general formula (I) react with aromaticcompounds having general formula (IX) (W ═—SnR′₃, —B(OH)₂, —B(OR)₂), togive condensation products having formula X as described in thefollowing scheme 4:

In literature there are various examples of these condensation reactions(Chem. Mater. 2006, 18, 3151-3161; Chem. Eur. Journal 2009, 15, 4906).The Suzuki reactions (W═—B(OH)₂, —B(OR)₂) and Stille reactions(W═—SnR′₃) are catalyzed by palladium complexes, such as Pd(PPh₃)₄,PdCl₂(PPh₃)₂, the catalysts can also be prepared in situ, starting fromPdCl₂ or Pd(OAc)₂ and the suitable phosphine (for example,triphenylphosphine (PPh₃, tris-ortho-tolylphosphine,tris-para-tolylphosphine). The molar ratios (I):(IX) between thereagents range from 1:2 to 1:4. The catalyst is used with molar ratios(I):cat. ranging from 1:0.008 to 1:0.02.

The reaction can be carried out in ether solvents (for exampledimethoxyethane, tetrahydrofuran), dipolar aprotic solvents (for exampleN,N-dimethylformamide, N-methylpyrrolidone) or hydrocarbon solvents suchas toluene, xylene, etc. In the case of the Suzuki reaction, whenW═—B(OH)₂, —B(OR)₂, the presence of a base is necessary (for example,sodium or potassium bicarbonate, sodium or potassium carbonate) used inmolar ratios I:base ranging from 1:1 to 1:20. The base is generallydissolved in degassed water. The aqueous solution can have aconcentration ranging from 1M to 3M, preferably 2M. The reaction iscarried out at temperatures ranging from 10 to 200° C., preferably from30 to 150° C. At the end of the reaction, the condensation product (X)is isolated and purified by elution on a chromatographic column ofneutral alumina.

The product X thus obtained is subsequently halogenated by normalhalogenation techniques of aromatic systems, as described in scheme 5:

The reagents generally used are bromine (Synth. Met. 2010, 160-354);N-halogensuccinimides such as N-bromosuccinimide, N-iodosuccinimide(Chem. Mater. 2006, 18, 3151-3161; Tele 2010, 51, 205). At the end ofthe reaction the product is isolated and purified by elution on achromatographic column of neutral alumina.

The process for obtaining the conjugated water-solublepolymer/copolymer, object of the present invention, provides for thereaction of at least one compound (I) or (II) with one or moreco-monomers selected from those described hereunder:

wherein

-   -   R₃-R₁₀ equal or different from each other, are hydrogen atoms;        C₁-C₃₇ alkyls, possibly branched, such as, for example, methyl,        ethyl, propyl, butyl, hexyl, octyl, decyl, dodecyl, tetradecyl,        hexadecyl, octadecyl, eicosyl, 2-ethylhexyl, 2-ethyloctyl,        2-ethyldecyl, 2-ethyldodecyl, 4-butylhexyl, 4-butyloctyl,        4-butyldecyl, 4-butyldodecyl, 2-hexyloctyl, 2-hexyldecyl,        4-hexyldecyl, isopropyl, 1-ethylpropyl, 1-butylpentyl,        1-hexylheptyl, 1-octylnonyl, 1-dodecyltridecyl,        1-hexadecylheptadecyl, 1-octadecyl-nonadecyl; if the radical is        linked to a carbon atom, R₃-R₁₀ can be —OC₁—OC₁₆ alkoxyl groups.    -   Y is a polymerizable group by means of a reaction selected from        those of Suzuki, Stille, Heck or Yamamoto, selected from —Br,        —Cl, —I, —O—(SO₂)—CF₃, —B(OH)₂, —B(OR′)₂, —SnR′₃, —B(OR″O),        vinyl, with R′ C₁-C₆ alkyl radical and R″ ethylene radical,        possibly substituted with C₁-C₂ alkyl groups.

The polymerization reaction takes place by resorting to a condensationreaction catalyzed by a derivative of a transition metal, which could bePalladium, in the case of Suzuki, Stille and Heck reactions, or Nickelin the case of a Yamamoto reaction.

Suzuki, Stille, Heck and Yamamoto reactions are known by experts in thefield and are described in Chem. Rev., 1995, 95, 2457; J. Am. Chem.Soc., 1995, 117, 12426; J. Poly. Sci., Polym. Lett. Ed., 1980. 18, 9;Makromol. Chem., 1988, 189, 119.

The Suzuki polymerization provides, in its most general form, thereaction between a monomer having boron functionalities (acid or ester)with a monomer carrying halogens, such as bromine or iodine, or atrifluoromethanesulfonate group. The reaction can be carried out in ahomogeneous solution (with a solvent selected, for example, fromtetrahydrofuran, dioxane, dimethylformamide, toluene, etc.) or inmixtures of an organic solvent with water. In this second case, aphase-transfer agent, such as a tetra-alkylammonium salt, is generallyused.

The reaction takes place in the presence of bases, such as sodiumcarbonate, sodium bicarbonate, tetra-alkylammonium hydroxides, caesiumfluoride and is catalyzed by coordination complexes of palladium, suchas palladium tetrakis(triphenylphosphine) or palladiumtetrakis(o-tolylphosphine), which can possibly also be obtained in situstarting from a palladium salt such as palladium acetate or palladiumchloride and a phosphine.

The Stille polymerization provides, in its most general form, thereaction between a monomer having trialkylstannyl functionalities with amonomer carrying halogens such as bromine or iodine. The reaction iscarried out in a homogeneous solution (tetrahydrofuran, dioxane,dimethylformamide, toluene). The reaction is catalyzed by coordinationcomplexes of palladium, such as palladium tetrakis(triphenylphosphine)or palladium tetrakis(o-tolylphosphine), which can possibly also beobtained in situ starting from a palladium salt such as palladiumacetate or palladium chloride and a phosphine

The Yamamoto polymerization provides, in its most general form, thereaction of a monomer carrying halogens such as bromine or iodine. Thereaction is carried out in an organic solvent and is catalyzed bycoordination complexes of nickel, for example cyclooctadienyl nickel.

The Heck polymerization provides, in its most general form, the reactionbetween a monomer having vinyl functionalities with a monomer carryinghalogens such as bromine or iodine. The reaction is carried out in anorganic solvent and is catalyzed by coordination complexes of palladium,such as palladium tetrakis(triphenylphosphine) or palladiumtetrakis(o-tolylphosphine), which can possibly also be obtained in situstarting from a palladium salt such as palladium acetate or palladiumchloride and a phosphine.

Once the copolymer has been obtained, and after isolating it usingmethods known to experts in the field, the resulting product is treatedunder acid hydrolysis conditions, for example in the presence ofalcohols such as methanol, ethanol, butanol, etc; or ketones, such asacetone, and water or mixtures of these solvents. The reaction iscarried out in an acid environment by hydrochloric acid orp-toluenesulfonic acid, generally HCl, to transform the dioxolane groupspresent along the chain into the corresponding diol groups:

The hydrolysis of ketals/acetals is part of the known art of organicsynthesis (Protective Groups in Organic Synthesis—T. W. Greene 1981,page 73.

The final copolymer proves to be soluble in water, alcohols orwater/alcohol, water/acetone, water/THF mixtures and can be used, incombination with an acceptor compound soluble in the same solvent, forexample a functionalized fullerene, for the formation of thin layers forsolar cells.

Some illustrative and non-limiting examples are provided for a betterunderstanding of the present invention and for its practical embodiment.

EXAMPLE 1 Synthesis of 2,7-dibromo-9,9-bis(3′-bromopropyl)fluoreneIntermediate

The following products are added, in an inert atmosphere, to a solutionof 2,7-dibromofluorene (10.0 g, 31.06 mmoles) in 40 ml of1,3-dibromopropane: first sodium hydroxide (30.0 g, 750.0 mmoles)dissolved in 60 ml of water and finally 0.2 g of tetrabutylammoniumbromide. The temperature is brought to 100° C. After 6 hours, after theaddition of water, extraction is effected with dichloromethane. Afterwashing the organic phase with water until neutrality, said organicphase is anhydrified on sodium sulfate. The dichloromethane and1,3-dibromopropane in excess are removed by distillation at reducedpressure. After purification by elution on a chromatographic silica gelcolumn (eluent: heptane/ethyl acetate=99/1), 5.2 g of2,7-dibromo-9,9-bis(3′-bromopropyl)fluorene are obtained (yield=30%).

Synthesis of2,7-dibromo-9,9-bis{3-[(2,2-dimethyl-1,3-dioxolan-4-yl)methoxy]propyl}fluorene

Potassium terbutylate (3.0 g, 26.7 mmoles) are added, in an inertatmosphere, to a solution of solketal (3.5 g, 26.7 mmoles) in 50.0 ml of1,2-dimethoxyethane. After 20 minutes, 5.0 g of2,7-dibromo-9,9-bis(3′-bromopropyl)fluorene (5.0 g, 8.9 mmoles)dissolved in 15.0 ml of 1,2-dimethoxyethane are added.

After 8 hours, after removing 1,2-dimethoxyethane by distillation atreduced pressure, the residue is recovered with ethyl acetate and iswashed with water until neutrality. After anhydrifying the organic phaseon sodium sulfate, the solvent is removed by distillation at reducedpressure. After purification by elution on a chromatographic aluminacolumn (heptane/ethyl acetate=95/5), 4.0 g of2,7-dibromo-9,9-bis{3-[(2,2-dimethyl-1,3-dioxolan-4-yl)methoxy]propyl}fluoreneare obtained (yield=74%).

EXAMPLE 2 Synthesis of 2,5-dibromo-3-methylthiophene First Intermediate

N-bromosuccinimide (20.0 g, 113.0 mmoles) is added, in an inertatmosphere to 3-methylthiophene (5.0 g, 51.0 mmoles) dissolved in 40 mlof tetrahydrofuran and 40 ml of acetic acid. After 1 hour, water isadded and extraction is effected with ethyl ether.

After washing the organic phase to neutrality, first with water and thenwith a saturated aqueous solution of sodium bicarbonate, said organicphase is anhydrified on sodium sulfate. The solvent is distilled atreduced pressure. 9.7 g of 2,5-dibromo-3-methylthiophene are obtained(yield=75%)

Synthesis of 2,5-dibromo-3-bromomethylthiophene Second Intermediate

The following products are added, in an inert atmosphere to a solutionof 2,5-dibromo-3-bromomethylthiophene (5.6 g, 22.0 mmoles) in 50 ml ofcarbon tetrachloride: N-bromosuccinimide (4.4 g, 24.9 mmoles) andfinally 50 mg of dibenzoylperoxide. After 7 hours, water is added andextraction is effected with ethyl acetate. After washing the organicphase to neutrality with water, said organic phase is anhydrified onsodium sulfate. After removing the solvent by distillation at reducedpressure, 5.0 g of 2,5-dimethyl-3-bromomethylthiophene are obtained(yield=70%).

Synthesis of4-{[(2,5-dibromo-3-thienyl)methoxy]methyl}-2,2-dimethyl-1,3-dioxolane

Potassium terbutylate (2.6 g, 23.2 mmoles) are added, in an inertatmosphere, to a solution of solketal (3.1 g, 23.5 mmoles) in 35.5 ml of1,2-dimethoxyethane. After 15 minutes,2,5-dimethyl-3-bromomethylthiophene (5.0 g, 15.0 mmoles) dissolved in 15ml of 1,2-dimethoxyethane, are added dropwise.

After 3 hours, the 1,2-dimethoxyethane is removed by distillation atreduced pressure, the residue is recovered with water and extracted withethyl acetate. After washing the organic phase with water untilneutrality, said organic phase is anhydrified on sodium sulfate. Thesolvent is removed by distillation at reduced pressure. Afterpurification by elution on an alumina column (heptane/ethylacetate=95/5), 4.0 g of4-{[(2,5-dibromo-3-thienyl)methoxy]methyl}-2,2-dimethyl-1,3-dioxolaneare obtained (yield=70%).

EXAMPLE 3 Synthesis of 3,6-dibromo-9-(3′-bromopropyl)carbazoleIntermediate

The following products are added, in an inert atmosphere, to a solutionof 3,6-dibromocarbazole (2.5 g, 7.74 mmoles) in 13 ml of toluene:potassium hydroxide (6.5 g, 98 mmoles) dissolved in 13 ml of water,tetrabutylammonium bromide and finally 1,3-dibromopropane (9.9 g, 49.2mmoles).

The temperature is brought to 70° C. After 3 hours, water is added andextraction is effected with ethyl acetate. After washing the organicphase with water to neutrality, said organic phase is anhydrified onsodium sulfate. After removing the solvent by distillation at reducedpressure 2.5 g of 3,6-dibromo-9-(3′-bromopropyl) carbazole are obtained(yield=75%).

Synthesis of3,6-dibromo-9-{3-[(2,2-dimethyl-1,3-di-oxolan-4-yl)methoxy]propyl}-9H-carbazole

Potassium terbutylate (0.8 g, 7.1 mmoles) are added, in an inertatmosphere, to a solution of solketal (0.9 g, 7.1 mmoles) in 10 ml of1,2-dimethoxyethane. After 15 minutes,3,6-dibromo-9-(3′-bromopropyl)carbazole (2.1 g, 4.7 mmoles) dissolved in10 ml of 1,2-dimethoxyethane, are added dropwise. After hours, the1,2-dimethoxyethane is removed by distillation at reduced pressure, theresidue is recovered with water and extracted with ethyl acetate. Afterwashing the organic phase with water until neutrality, said organicphase is anhydrified on sodium sulfate. The solvent is removed bydistillation at reduced pressure. After purification by elution on analumina column (heptane/ethyl acetate=9/1), 1.6 g of3,6-dibromo-9-{3-[(2,2-dimethyl-1,3-di-oxolan-4-yl)methoxy]propyl}-9H-carbazoleare obtained (yield=70%).

EXAMPLE 4 Synthesis of the random copolymerpoly{(2,1,3-benzothiadiazole)-alt-[(3-(4-sodiumsulfobutoxy)methyl-thiophene)-co-(9,9-bis-(3-((2,2-dimethyl-1,3-dioxolan-4-yl)methoxy)propyl)fluorene)]}

The following products are introduced in an inert atmosphere into a 50ml two-necked flask equipped with a magnetic stirrer and reflux cooler:

-   -   324.3 mg (0.485 mmoles) of        2,7-dibromo-9,9-bis{3-[(2,2-dimethyl-1,3-dioxolan-4-yl)methoxy]propyl}fluorene;    -   373.80 mg (0.963 mmoles) of        4,7-bis(pinacolboronic-2,1,3-benzothiadiazole) ester;    -   200.6 mg (0.482 mmoles) of        [(2,5-dibromo-3-thienyl)methoxy]sodium butanesulfonate;    -   10 ml of distilled THF (tetrahydrofuran);    -   1 ml of an aqueous solution 4 M of K₂CO₃;    -   a few drops of Aliquat 334.

The reaction mixture is heated to 70° C. for 15 minutes and thefollowing product is then added:

-   -   12 mg (0.01 mmoles) of Pd (0) tetrakis(triphenylphosphine);

The reaction mixture is left at this temperature for 40 hours. After 5hours the reaction is almost dry and a further 5 ml of THF are added.After 40 hours the mixture is cooled and the solvent removed bydistillation.

Hydrolysis ofpoly{(2,1,3-benzothiadiazole)-alt-[(3-(4-sodiumsulfobutoxy)methylthiophene)-co-(9,9-bis-(3-((2,2-dimethyl-1,3-dioxolan-4-yl)methoxy)propyl)fluorene)]}

The following products are introduced into a 250 ml two-necked flask:

-   -   600 mg of random copolymer between        2,7-dibromo-9,9-bis{3-[(2,2-dimethyl-1,3-dioxolan-4-yl)methoxy]propyl}-fluorene,        4,7-bis pinacolboronic-2,1,3-benzothiadiazole ester and        [(2,5-dibromo-3-thienyl)methoxy]sodium butanesulfonate,        previously prepared,    -   45 ml of acetone;    -   35 ml of water;    -   5 ml of HCl at 37%.

After 18 hours, the mixture is cooled to room temperature. The solutionis at neutral pH, as resulting from a litmus paper test. The solvent isthen removed by distillation. The polymer is re-dissolved in a solutionconsisting of 45 ml of acetone and 5 ml of distilled water.

The solution containing the polymer is transferred to a dialysismembrane with a cut-off at 1,200 Da and dialyzed for 2 days in a 1 lcylinder also containing an acetone/water solution in a weight ratio of9:1.

The solvent is removed from the solution containing the polymer bydistillation. 375 mg of a dark red polymer are obtained.

The NMR spectrum shows the disappearance of the signals due to themethyl groups of the dioxolane groups and their transformation intoglycol groups.

1. Monomers having the following general structure (I):

wherein: Ar is a C₆-C₁₂ aromatic radical, a C₁₂-C₁₈ polycyclic aromaticradical, or Ar is a heteroaromatic radical containing one or moreheteroatoms such as S, N, Se, O, optionally polycondensed, X is a groupwhich can be polymerized by means of a reaction selected from Suzuki,Stille, Heck or Yamamoto reactions, selected from —Br, —Cl, —I,—O—(SO₂)—CF₃, —B(OH)₂, —B(OR′)₂, —SnR′₃, —B(OR″O) and vinyl, with R′ aC₁-C₆ alkyl radical and R″ an ethylene radical, optionally substitutedwith C₁-C₂ alkyl groups; R₁ and R₂, the same or different, can be ahydrogen atom or a C₁-C₆ alkyl radical; R is a divalent C₁-C₁₂ alkyleneradical; n ranges from 1 to
 4. 2. Monomers having the following generalstructure (II):

wherein R, R₁, R₂, Ar, X, n have the same meanings as defined in claim1; and Ar′ represents a heteroaromatic radical containing a heteroatomsuch as S, N, Se; m=1 or
 2. 3. The monomers according to claim 2,wherein Ar is a radical deriving from benzene, fluorene, thiophene,carbazole, dithienocyclopentadiene or from phenothiazine.
 4. Themonomers according to claim 2, wherein Ar′ is a radical deriving fromthiophene, thieno-thiophene, thiazole, carbazole,dithienocyclopentadiene or from phenothiazine. 5-7. (canceled)
 8. Aprocess for the synthesis of monomers having formula (II) comprising thecondensation reaction according to the following scheme:

wherein W═SnR′₃—B(OH)₂, —B(OR)₂ followed by halogenation of thederivative obtained.
 9. The process according to claim 8, wherein themolar ratios (I):(IX) used are between 1:2 and 1:4.
 10. The processaccording to claim 8, wherein the reaction is carried out attemperatures ranging from 10 to 200° C., preferably from 30 to 150° C.11. A process for the preparation of a conjugated polymer or copolymer,soluble in water, comprising the reaction of at least one compound (I)or (II) with one or more co-monomers selected from those describedhereunder:

wherein R₃-R₁₀ have the meaning expressed in the description and Y is agroup which can be polymerized by means of a reaction selected fromthose of Suzuki, Stille, Heck or Yamamoto, and the subsequent acidhydrolysis of the polymer or copolymer obtained.
 12. The processaccording to claim 11, wherein the polymerization reaction is acondensation reaction, catalyzed by a derivative of a transition metal,selected from palladium, in the case of Suzuki, Stille and Heckreactions, or nickel, in the case of a Yamamoto reaction.